The present invention relates to curable compositions having high solids and low VOC. These curable compositions are especially useful as coatings and may typically be used as primers, topcoats or as clearcoats and/or basecoats in clearcoat/basecoat compositions. In particular, this invention is directed to a coating composition providing extended pot life and excellent cure and consisting of the combination of (i) at least one imine having the structure ##STR1## wherein n is 0 to 30. R.sub.1 and R.sub.2 are selected from the group consisting of hydrogen, alkyl, aryl, cycloaliphatic, and substituted alkyl, aryl, and cycloaliphatic groups; and R.sub.1 and R.sub.2 may be the same or different; and R.sub.3 is selected from the group consisting of aliphatic, aromatic, arylaliphatic, and cycloaliphatic groups and which may also contain O, N, S, or Si; (ii) a polyisocyanate having an average of at least two isocyanate groups per molecule; (iii) at least one polyaspartic ester; and (iv) an anhydride functional polymer; wherein the coating composition is substantially free of hydroxyl functionality.
Two-component curable mixtures comprising polyisocyanates and active hydrogen-containing compounds, such as polyols or polyamines, are well-known in the art to provide excellent performance and cure at low temperatures. However, due to the reactivity of the isocyanates and the active hydrogen-containing compounds, it is often difficult to obtain long pot-lives of the mixture of polyisocyanate and active hydrogen-containing material and yet still enjoy the benefits of rapid cure. This is especially true for low VOC materials, which will incorporate relatively low levels of solvent and will frequently involve low molecular weight, but highly reactive, starting materials.
Accordingly, it is an object of the present invention to provide a two component coating composition having extended pot-life and excellent cure. It is a further object of the present invention to provide an ambient cured coating composition having relatively low viscosity and low VOC. It is an even further object of the present invention to provide an ambient cured coating composition which is capable of providing an excellent cure in very dry and cool ambient conditions.